Processes for the preparation of titanium phthalocyanines

ABSTRACT

Disclosed are various titanyl phthalocyanine polymorphs such as Type I, Type II, Type III, Type IV, Type Z-1, Type Z-2, and Type X, which phthalocyanines can be prepared by dissolving a titanyl phthalocyanine in a solution of trifluoroacetic acid and a chlorinated hydrocarbon. There is then added to the resulting solution a solvent that will enable precipitation of the titanyl phthalocyanine. Subsequently, the titanyl phthalocyanine product can be separated from the solution by, for example, filtration and the product titanyl phthalocyanine obtained can be washed to remove any residual solvent.

BACKGROUND OF THE INVENTION

This invention is generally directed to titanyl phthalocyanines andprocessed for the preparation thereof, and more specifically the presentinvention is directed to processes for obtaining titanyl phthalocyaninepolymorphs or crystal forms, including the known Type I, Type II, TypeIII, and Type IV, reference for example U.S. Pat. No. 4,898,799, thedisclosure of which is totally incorporated herein by reference, as wellas novel crystal modifications thereof, such as X titanylphthalocyanines, and layered photoconductive members comprised of theaforementioned titanyl phthalocyanine polymorphs. In one embodiment, thepresent invention is directed to a process for the preparation oftitanyl phthalocyanines by initially providing a titanyl phthalocyanine,or accomplishing the preparation thereof by, for example, the reactionof titanium tetra(alkoxide) with diiminoisoindolene in a solvent such aschloronaphthalene; dissolving the resulting pigment in a solvent mixtureof trifluoroacetic acid and methylene chloride; and thereafterprecipitating the desired titanyl phthalocyanine polymorph by, forexample, adding with stirring the aforementioned mixture to water,separating the product therefrom by, for example, filtration, andwashing the product obtained. The titanyl phthalocyanines, especiallythe known polymorph IV and the X form, can be selected as organicphotogenerator pigments in photoresponsive imaging members containingcharge, especially hole transport layers such as arylamine holetransport molecules. The aforementioned photoresponsive imaging memberscan be negatively charged when the photogenerating layer is situatedbetween the hole transport layer and the substrate, or positivelycharged when the hole transport layer is situated between thephotogenerating layer and the supporting substrate. The layeredphotoconductor imaging members can be selected for a number of differentknown imaging and printing processes including, for example,electrophotographic imaging process, especially xerographic imaging andprinting processes wherein negatively charged or positively chargedimages are rendered visible with toner compositions of the appropriatecharge. Generally, the imaging members are sensitive in the wavelengthregions of from about 700 to about 850 nanometers, thus diode lasers canbe selected as the light source. Titanyl phthalocyanines may also beselected as intense blue light-stable colorants for use in coatings,such as paint, inks, and as near infrared absorbing pigments suitablefor use as IR laser optical recording materials.

Certain titanium phthalocyanine pigments have been known since at leastprior to the publication WW 2(PB 85172 Fiat Final Report 1313, Feb. 1,1948). However, unlike other phthalocyanines such as metalfree, copper,iron and zinc phthalocyanines, titanium phthalocyanines have had minimumcommercial use. Titanyl phthalocyanines or oxytitanium phthalocyaninesare known to absorb near-infrared light around 800 nanometers and anumber of such pigments have been illustrated in the prior art asmaterials for IR laser optical recording material, reference for exampleBASF German 3,643,770 and U.S. Pat. No. 4,458,004. The use of certaintitanium phthalocyanine pigments as a photoconductive material forelectrophotographic applications is known, reference for example BritishPatent Publication 1,152,655, the disclosure of which is totallyincorproated herein by reference. Also, U.S. Pat. No. 3,825,422illustrates the use of titanyl phthalocyanine as a photoconductivepigment in an electrophotographic process known as particleelectrophoresis. Additionally, the utilization of certain titanylphthalocyanines and substituted derivatives thereof in a dual layerelectrographic device is illustrated in EPO 180931, May 14, 1986.Moreover, the use of tetra- and hexadeca-flouro-substituted titanylphthalocyanine in an electrophotographic device is illustrated in U.S.Pat. No. 4,701,396. In Japanese Patent Publication 64-171771, August,1986, there is illustrated the use of titanyl phthalocyanine, which hasbeen treated with a hot solvent, in electrophotography. Further, inGerman 3,821,628 there is illustrated the utilization of certain titanylphthalocyanines, and other pigments in electrophotography, and whereinthe titanyl phthalocyanines have been purified primarily to reduce thelevel of ash, volatile contaminants and sodium to below specifiedlevels.

In the aforementioned documents, although synthesis and certainprocessing conditions were generally disclosed for the preparation ofthe titanyl phthalocyanine pigments, it is believed that there is noreference to certain crystal phases or polymorphs of the pigment. Asmentioned in the textbook Phthalocyanine Compounds by Moser and Thomas,the disclosure of which is totally incorporated herein by reference,polymorphism or the ability to form distinct solid state forms is wellknown in phthalocyanines. For example, metal-free phthalocyanine isknown to exist in least 5 forms designated as alpha, beta, pi, X andtau. Copper phthalocyanine crystal forms known as alpha, beta, gamma,delta, epsilon and pi are also described. These different polymorphicforms are usually distinguishable on the basis of differences in thesolid state properties of the materials which can be determined bymeasurements, such as Differential Scanning Calorimetry, InfraredSpectroscopy, Ultraviolet-Visible-Near Infrared spectroscopy andespecially, X-Ray Power Diffraction techniques. There appears to begeneral agreement on the nomenclature used to designate specificpolymorphs of commonly used pigments such as metal-free and copperphthalocyanine. However, this does not appear to be the situation withtitanyl phthalocyanines as different nomenclature is selected in anumber of instances. For example, reference is made to alpha, beta, A,B, C, y, and m forms of TiOPc (titanyl phthalocyanine) with differentnames being used for the same form in some situations. It is believedthat four main crystal forms of TiOPc are known, that is Types I, II,III, and IV. The X-ray powder diffraction traces (XRPDs) obtained fromthese 4 forms are shown in FIGS. 1A, 1B, 1C and 1D. Subclasses of theseforms with broad, more poorly resolved peaks than those shown in FIGS.1A, 1B, 1C and 1D can be envisioned, however, the basic features of thediffractograms indicate the major peaks in the same position althoughthe smaller peaks can be unresolved. This broadening of XRPD peaks isgenerally found in pigments having a very small particle size. In Table1 that follows, there is provided a listing of documents that disclosetitanyl phthalocyanine polymorpic forms classified as belonging to oneof the main types as indicated.

                  TABLE 1                                                         ______________________________________                                        Crystal                                                                              Other                                                                  Form   Names     Documents                                                    ______________________________________                                        Type I β    Toyo Ink Electrophotog. (Japan)                                               27, 533 (1988)                                                      β    Dainippon U.S. Pat. No. 4,728,592                                   β    Sanyo-Shikiso JOP 63-20365                                          A         Mitsubishi JOP 62-25685,-6,-7 Conference                                      Proceedings                                                         A         Konica "Japan Hardcopy 1989",                                                 103, (1989)                                                  Type II                                                                              α   Toyo Ink "Electrophoto (Japan)"                                               27, 533 (1988)                                                      α   Sanyo-Shikiso JOP 63-20365                                          α   Konica U.S. Pat. No. 4,898,799                                      α   Dainippon U.S. Pat. No. 4,728,592                                   α   Mita EU 314,100                                                     B         Mitsubishi JOP 62-25685,-6,-7                                       B         Konica "Japan Hardcopy 1989, 103, (1989)                     Type III                                                                             C         Mitsubishi OP 62-25685,-6,-7                                        C         Konica "Japan Hardcopy 1989, 103, (1989)                            m         Toyo Ink "Electrophoto (Japan)"                                               27, 533 (1988)                                               Type IV                                                                              y         Konica "Japan Hardcopy 1989",                                                 103, (1989)                                                         Unnamed   Konica U.S. Pat. No. 4,898,799                                      New Type  Sanyo-Shikiso JOP 63-20365                                   ______________________________________                                    

More specifically, the aforementioned documents illustrate, for example,the use of specific polymorphs of TiOPc in electrophotographic devices.Three crystal forms of titanyl phthalocyanine, differentiated by theirXRPDs, were specifically illustrated, identified as A, B, and C, whichit is believed are equivalent to Types I, II, and III, respectively. InJapanese 62-256865 there is disclosed, for example, a process for thepreparation of pure Type I involving the addition of titaniumtetachloride to a solution of phthalonitrile in an organic solvent whichhas been heated in advance to a temperature of from 160° to 300° C. InJapanese 62-256866, there is illustrated, for example, a method ofpreparing the aforementioned polymorph which involves the rapid heatingof a mixture of phthalonitrile and titanium tetrachloride in an organicsolvent at a temperature of from 100° to 170° C. over a time periodwhich does not exceed one hour. In Japanese 62-256867, there isdescribed, for example, a process for the preparation of pure Type II(B) titanyl phthalocyanine, which involves a similar method to thelatter except that the time to heat the mixture at from 100° to 170° C.,is maintained for at least two and one half hours. Types I and II, inthe pure form obtained by the process of the above publications,apparently afforded layered photoresponsive imaging members withexcellent electrophotographic characteristics.

In Mita EPO patent publication 314,100, there is illustrated thesynthesis of TiOPc by, for example, the reaction of titanium alkoxidesand diiminoisoindolene in quinoline or an alkylbenzene, and thesubsequent conversion thereof to an alpha Type pigment (Type II) by anacid pasting process, whereby the synthesized pigment is dissolved inconcentrated sulfuric acid, and the resultant solution is poured ontoice to precipitate the alpha-form, which is filtered and washed withmethylene chloride. This pigment, which was blended with varying amountsof metal free phthalocyanine, could be selected as the electric chargegenerating layer in layered photoresponsive imaging members with a highphotosensitivity at, for example, 780 nanometers.

In Sanyo-Shikiso Japanese 63-20365/86, reference is made to the knowncrystal forms alpha and beta TiOPc (Types II and I, respectively, it isbelieved), which publication also describes a process for thepreparation of a new form of titanyl phthalocyanine, which is apparentlynot named. This publication appears to suggest the use of the unnamedtitanyl phthalocyanine as a pigment and its use as a recording mediumfor optical discs. This apparently new form was prepared by treatingacid pasted TiOPc (Type II form, it is believed) with a mixture ofchlorobenzene and water at about 50° C. The resulting apparently newform is distinguished on the basis of its XRPD, which appears to beidentical to that shown in FIG. 1 for the Type IV polymorph.

In U.S. Pat. No. 4,728,592, there is illustrated, for example, the useof alpha ype TiOPc (Type II) in an electrophotographic device havingsensitivity over a broad wavelength range of from 500 to 900 nanometers.This form was prepared by the treatment of dichlorotitaniumphthalocyanine with concentrated aqueous ammonia and pyridine at refluxfor 1 hour. Also described in the aforementioned patent is a beta TypeTiOPc (Type l) as a pigment, which is believed to provide a much poorerquality photoreceptor.

In Konica Japanese 64-17066/89, there is disclosed, for example, the useof a new crystal modification of TiOPc prepared from alpha type pigment(Type II) by milling it in a sand mill with salt and polyethyleneglycol. This pigment had a strong XRPD peak at a value of 2 theta of27.3 degrees. This publication also discloses that this new form differsfrom alpha type pigment (Type II) in its light absorption and shows amaximum absorbance at 817 nanometers compared to alpha-type, which has amaximum at 830 nanometers. The XRPD shown in the publication for thisnew form is believed to be identical to that of the Type IV formpreviously described by Sanyo-Shikiso in JOP 63-20365. Theaforementioned Konica publication also discloses the use of this newform of TiOPc in a layered electrophotographic device having highsensitivity to near infrared light of 780 nanometers. The new form isindicated to be superior in this application to alpha type TiOPc (TypeII). Further, this new form is also described in U.S. Pat. No. 4,898,799and in a paper presented at the Annual Conference of Japan Hardcopy inJuly 1989. In this paper, this same new form is referred to as Type y,and reference is also made to Types I, II, and III as A, B, and C,respectively.

In the journal, Electrophotography (Japan) vol. 27, pages 533 to 538,Toyo Ink Manufacturing Company, there is disclosed, for example, alphaand beta forms of TiOPc (Types I and II, it is believed) and also thisjournal discloses the preparation of a Type m TiOPc, an apparently newform having an XRPD pattern which was distinct from other crystal forms.It is believed that his XRPD is similar to that for the Type III titanylphthalocyanine pigment but it is broadened most likely as the particlesize is much smaller than that usually found in the Type III pigment.This pigment was used to prepare photoreceptor devices having greatersensitivity at 830 nanometers than alpha or beta Type TiOPc (Type II orI, respectively).

Processes for the preparation of specific polymorphs of titanylphthalocyanine, which require the use of a strong acid such as sulfuricacid, are known, and these processes, it is believed, are not easilyscable. One process as illustrated in Konica Japanese Laid Open on Jan.20, 1989 as 64-17066 (U.S. Pat. No. 4,898,799 appears to be itsequivalent), the disclosure of which is totally incorporated herein byreference, involves, for example, the reaction of titanium tetrachlorideand phthalodinitrile in 1-chloronaphthalene solvent to producedichlorotitanium phthalocyanine which is then subjected to hydrolysis byammonia water to enable the Type II polymorph. This phthalocyanine ispreferably treated with an electron releasing solvent such as2-ethoxyethanol, dioxane, N-methylpyrrolidone, followed by subjectingthe alpha-titanyl phthalocyanine to milling at a temperature of from 50°to 180° C. In a second method described in the aforementioned JapanesePublication, there is disclosed the preparation of alpha type titanylphthalocyanine with sulfuric acid. Another method for the preparation ofType IV titanyl phthalocyanine involves the addition of an aromatichydrocarbon, such as chlorobenzene solvent to an aqueous suspension ofType II titanyl phthalocyanine prepared by the well-known acid pastingprocess, and heating the resultant suspension to about 50° C. asdisclosed in Sanyo-Shikiso Japanese 63-20365, Laid Open in Jan. 28,1988. In Japanese 171771/1986, Laid Open Aug. 2, 1986, there isdisclosed the purification of metallophthalocyanine by treatment withN-methylpyrrolidone.

To obtain a TiOPc-based photoreceptor having high sensitivity to nearinfrared light, it is believed necessary to control not only the purityand chemical structure of the pigment, as is generally the situationwith organic photoconductors, but also to prepare the pigment in thecorrect crystal modification. The disclosed processes used to preparespecific crystal forms of TiOPc, such as Types I, II, III and IV areeither complicated and difficult to control as in the preparation ofpure Types I and II pigment by careful control of the synthesisparameters by the processes described in Mitsubishi Japanese 62-25685,-6 and -7, or involve harsh treatment such as sand milling at hightemperature, reference Konica U.S. Pat. No. 4,898,799; or dissolution ofthe pigment in a large volume of concentrated sulphuric acid, a solventwhich is known to cause decomposition of metal phthalocyanines,reference Sanyo-Shikiso Japanese 63-20365, and Mita EPO 314,100.

In the present application, there is disclosed, for example, in oneembodiment an economical method for the preparation of polymorphs ofTiOPc, specifically the Type I, II, III and IV polymorphs, and at leastthree new crystal forms which have not been described previously. Thismethod is an improvement over the prior art in that, for example, inembodiments thereof it is not complex, is rapid, does not require theuse of harsh reagents such as sulfuric acid or the use of energyintensive processes such as sand milling. The process of the presentinvention in one embodiment involves dissolving Type l titanylphthalocyanine (TiOPc), prepared, for example, by the reaction ofdiiminoisoindolene with titanium tetrapropoxide in a N-methylpyrrolidonesolvent in a solvent composition comprised of a strong organic acid suchas trifluoroacetic acid and a solvent such as methylene chloride (thetitanyl phthalocyanine pigment is highly soluble in this mixture,dissolves within minutes and is stable for at least about two weeks);followed by a reprecipitation of the pigment into a second solventsystem. The composition of the precipitant solvent primarily determineswhich polymorphic form of TiOPc can be obtained. The desired polymorphicform can be isolated by a simple filtration process and can be washedwith water and/or organic solvents to attain a suitable degree ofpurity.

Generally, layered photoresponsive imaging members are described in anumber of U.S. patents, such as U.S. Pat. No. 4,265,900, the disclosureof which is totally incorporated herein by reference, wherein there isillustrated an imaging member comprised of a photogenerating layer, andan aryl amine hole transport layer. Examples of photogenerating layercomponents include trigonal selenium, metal phthalocyanines, vanadylphthalocyanines, and metal free phthalocyanines. Additionally, there isdescribed in U.S. Pat. No. 3,121,006 a composite xerographicphotoconductive member comprised of finely divided particles of aphotoconductive inorganic compound dispersed in an electricallyinsulating organic resin binder. The binder materials disclosed in the'006 patent comprise a material which is incapable of transporting forany significant distance injected charge carriers generated by thephotoconductive particles.

Photoresponsive imaging members with squaraine photogenerating pigmentsare also known, reference U.S. Pat. No. 4,415,639. In this patent thereis illustrated a photoresponsive imaging member with a substrate, a holeblocking layer, an optional adhesive interface layer, an organicphotogenerating layer, a photoconductive composition capable ofenhancing or reducing the intrinsic properties of the photogeneratinglayer, and a hole transport layer. As photoconductive compositions forthe aforementioned member, there can be selected various squarainepigments, including hydroxy squaraine compositions. Moreover, there isdisclosed in U.S. Pat. No. 3,824,099 certain photosensitive hydroxysquaraine compositions.

The use of selected perylene pigments as photoconductive substances isalso known. There is thus described in Hoechst European PatentPublication 0040402, DE3019326, filed May 21, 1980, the use ofN,N'-disubstituted perylene-3,4,9,10-tetracarboxyldiimide pigments asphotoconductive substances. Specifically, there is, for example,disclosed in this publicationN,N'-bis(3-methoxypropyl)perylene-3,4,9,10-tetracarboxyldiimide duallayered negatively charged photoreceptors with improved spectralresponse in the wavelength region of 400 to 700 nanometers. A similardisclosure is revealed in Ernst Gunther Schlosser, Journal of AppliedPhotographic Engineering, Vol. 4, No. 3, page 118 (1978). There are alsodisclosed in U.S. Pat. No. 3,871,882 photoconductive substancescomprised of specific perylene-3,4,9,10-tetracarboxylic acid derivativedyestuffs. In accordance with the teachings of this patent, thephotoconductive layer is preferably formed by vapor depositing thedyestuff in a vacuum. Also, there is specifically disclosed in thispatent dual layer photoreceptors with perylene-3,4,9,10-tetracarboxylicacid diimide derivatives, which have spectral response in the wavelengthregion of from 400 to 600 nanometers. Also, in U.S. Pat. No. 4,555,463,the disclosure of which is totally incorporated herein by reference,there is illustrated a layered imaging member with a chloroindiumphthalocyanine photogenerating layer. In U.S. Pat. No. 4,587,189, thedisclosure of which is totally incorporated herein by reference, thereis illustrated a layered imaging member with a perylene pigmentphotogenerating component. Both of the aforementioned patents disclosean aryl amine component as a hole transport layer.

Moreover, there are disclosed in U.S. Pat. No. 4,419,427 electrographicrecording mediums with a photosemiconductive double layer comprised of afirst layer containing charge carrier perylene diimide dyes, and asecond layer with one or more compounds which are charge transportingmaterials when exposed to light, reference the disclosure in column 2,beginning at line 20. Also of interest with respect to this patent isthe background information included in columns 1 and 2, wherein perylenedyes of the formula illustrated are presented.

Furthermore, there is presented in U.S. Pat. No. 4,514,482, entitledPhotoconductive Devices Containing Perylene Dye Compositions, thedisclosure of which is totally incorporated herein by reference, anambipolar imaging member comprised of a supporting substrate, aphotoconductive layer comprised of specific perylene dyes, which dyesare dispersed in a polymeric resinous binder composition; and as a toplayer a specific aryl amine hole transporting substance dispersed in aninactive resinous binder.

In a copending application U.S. Ser. No. 537,714, the disclosure ofwhich is totally incorporated herein by reference, there are illustratedphotoresponsive imaging members with photogenerating titanylphthalocyanine layers prepared by vacuum deposition. It is indicated inthis copending application that the imaging members comprised of thevacuum deposited titanyl phthalocyanines and aryl amine holetransporting compounds exhibit superior xerographic performance as lowdark decay characteristics result and higher photosensitivity isgenerated, particularly in comparison to several prior art imagingmembers prepared by solution coating or spray coating, reference forexample, U.S. Pat. No. 4,429,029 mentioned hereinbefore.

In copending application U.S. Ser. No. 533,265, the disclosure of whichis totally incorporated herein by reference, there is illustrated aprocess for the preparation of phthalocyanine composites which comprisesadding a metal free phthalocyanine, a metal phthalocyanine, a metalloxyphthalocyanine or mixtures thereof to a solution of trifluoroacetic acidand a monohaloalkane; adding to the resulting mixture a titanylphthalocyanine; adding the resulting solution to a mixture that willenable precipitation of said composite; and recovering thephthalocyanine composite precipitated product. Illustrated in copendingapplication U.S. Ser. No. 537,740 is a process which comprises adding apigment to a solution of trihaloacetic acid and toluene; adding thesolution to a nonsolvent for the pigment; and separating the productfrom the solution.

The disclosures of all of the aforementioned publications, laid openapplications, and patents are totally incorporated herein by reference.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide processes for thepreparation of titanyl phthalocyanines with many of the advantagesillustrated herein.

It is yet another feature of the present invention to provideeconomically scalable processes for the preparation of titanylphthalocyanines.

Another feature of the present invention relates to the preparation oftitanyl phthalocyanine polymorphs, including those known as Type I, TypeII, and Type IV.

Further, another feature of the present invention relates to thepreparation of photogenerating titanyl phthalocyanines by thesolubilization of titanyl phthalocyanines followed by reprecipitationinto solvent compositions.

Moreover, another feature of the present invention relates to thepreparation of titanyl phthalocyanines with high purities, and the usethereof in electophotographic processes.

Additionally, another feature of the present invention relates to thepreparation of titanyl phthalocyanine polymorphs in acceptable yieldsof, for example, exceeding about 75 percent in embodiments of thepresent invention.

Yet another feature of the present invention is the high degree ofversatility of the described process in that it can allow thepreparation of at least 7 different polymorphs of TiOPc with minormodifications of the process.

Another feature of the present invention is that the process describedherein in an embodiment allows the preparation of a new crystal form ofTiOPc, designated X-form, which is distinguishable from previouslydescribed forms of the basis of its XRPD pattern, reference, forexample, FIG. 4.

Additionally, another feature of the present invention is that theprocess allows the preparation of a new crystal form of TiOPc, Type Z-1having the XRPD pattern shown in FIG. 2.

Yet another feature of the present invention is the provison ofprocesses that affords a crystal form of TiOPc, Type Z-2 having the XRPDpattern shown in FIG. 3.

Another feature of the present invention is that it provides for thepreparation of TiOPc polymorphs having a small particle size of about0.1 micron which is advantageous for the preparation ofelectrophotographic devices since, for example, it can be easilydispersed in coating compositions.

Another feature of the present invention in an embodiment thereofresides in the preparation of TiOPc polymorphs having a small particlesize of about 0.1 microns which is advantageous for the preparation ofelectrophotographic devices since, for example, the prepared polymorphscan be easily dispersed in coating compositions.

Yet another feature of the present invention is that mild conversionconditions can be selected which do not cause decomposition of thetitanyl phthalocyanine pigment.

A further specific object of the present invention resides in theprovision of photoresponsive imaging members with an aryl amine holetransport layer, and a photogenerator layer comprised of titanylphthalocyanine pigment obtained by the processes illustrated herein.

A further specific object of the present invention resides in theprovision of photoresponsive imaging members with an aryl amine holetransport layer, and a photogenerator layer comprised of the titanylphthalocyanine pigments X-form, Type Z-1, or Type Z-2.

These other objects and features of the present invention areaccomplished in embodiments thereof by the provision of certainphthalocyanines, processes for the preparation of titanylphthalocyanines and photoresponsive imaging members thereof. Morespecifically, in one embodiment of the present invention there areprovided processes for the preparation of titanyl phthalocyanine (TiOPc)polymorphs which comprises the solubilization of a titanylphthalocyanine in a mixture of trifluoroacetic acid and methylenechloride, precipitation of the desired titanyl phthalocyanine, such asType IV, separation by, for example, filtration, and optionallysubjecting the product to washing. The product can be identified byvarious known means including X-ray powder diffraction, (XRPD).

One embodiment of the present invention is directed to processes for thepreparation of titanyl phthalocyanines, which comprise the reaction oftitanium tetrapropoxide with diiminoisoindolene in N-methylpyrrolidonesolvent to provide Type I, or β-type titanyl phthalocyanine asdetermined by X-ray powder diffraction; dissolving the resulting titanylphthalocyanine in a mixture of trifluoroacetic acid and methylenechloride; adding the resulting mixture to a stirred organic solvent,such as methanol, or to water; separating the resulting precipitate by,for example, vacuum filtration through a glass fiber paper in a Buchnerfunnel; and washing the titanyl phthalocyanine product.

Examples of titanyl phthalocyanine reactants that can be selected ineffective amounts of, for example, from about 1 weight percent to about40 percent by weight of the trifluoroacetic acidic solvent mixtureinclude known available titanyl phthalocyanines; titanyl phthalocyaninessynthesized from the reaction of titanium halides such as titaniumtrichloride, titanium tetrachloride or tetrabromide; titaniumtetraalkoxides such as titanium tetra-methoxide, -ethoxide, -propoxide-,-butoxide, -isopropoxide and the like; and other titanium salts withcompounds such as phthalonitrile and diiminoisoindolene in solvents suchas 1-chloronaphthalene, quinoline, N-methylpyrrolidone, andalkylbenzenes such as xylene at temperatures of from about 120° to about300° C.; specific polymorphs of titanyl phthalocyanine such as Type I,II, III, and IV, the preparation of which, for example, is described inthe literature; or any other suitable polymorphic form of TiOPc;substituted titanyl phthalocyanine pigments having from 1 to 16substituents attached to the outer ring of the compound, saidsubstituent being, for example, halogens such as chloro-, bromo-, iodo-and fluoro-, alkyls with from 1 to about 6 carbon atoms such as methyl-,ethyl-, propyl-, isopropyl-, butyl-, pentyl-, and hexyl-; nitro, amino,alkoxy and alkylthio, such as methoxy-, ethoxy- and propylthio-groups;and mixtures thereof.

As the solvent mixture, there can be selected a strong organic acid,such as a trihaloacetic acids, including trifluoroacetic acid ortrichloroacetic acid, and a cosolvent, such as an alkylene halide, suchas methylene chloride, chloroform, trichloroethylene, bromoform andother short chain halogenated alkanes and alkenes with from 1 to about 6carbon atoms and from 1 to about 6 halogen atoms includingchlorofluorocarbons and hydrochlorofluorocarbons; haloaromatic compoundssuch as chlorobenzene, dichlorobenzene, chloronaphthalene,fluorobenzene, bromobenzene, and benzene; alkylbenzenes such as tolueneand xylene; and other organic solvents which are miscible with strongorganic acids and which will effectively dissolve the titanylphthalocyanine in effective amounts of, for example, a ratio of fromabout 1 to 50 parts of acid to about 50 parts of cosolvent such asmethylene chloride. In an embodiment of the present invention, apreferred solvent mixture is comprised of trifluoroacetic acid andmethylene chloride in a ratio of from about 5 parts acid to about 95parts methylene chloride to 25 parts acid to 75 parts of methylenechloride.

Subsequent to solubilization with the above solvent mixture and stirringfor an effective period of time of, for example, from about 5 minutes toseveral days, the resulting mixture is added to a solvent that willenable precipitation of the desired titanyl phthalocyanine polymorph,such as Type IV, which solvent is comprised of an alcohol such as analkylalcohol including methanol, ethanol, propanol, isopropanol,butanol, n-butanol, pentanol and the like; ethers such as diethyl etherand tetrahydrofuran; hydrocarbons such as pentane, hexane and the likewith, for example, from about 4 to about 10 carbon atoms; aromaticsolvents such as benzene, toluene, xylene, halobenzenes such aschlorobenzene, and the like; carbonyl compounds such as ketones such asacetone, methyl, ethyl ketone, and butyraldehyde; glycols such asethylene and propylene glycol and glycerol; polar aprotic solvents suchas dimethyl sulfoxide, dimethylformamide and N-methylpyrrolidone; andwater, as well as mixtures of the aforementioned solvents, followed byfiltration of the titanyl phthalocyanine polymorph, and washing withvarious solvents such as, for example, deionized water and an alcoholsuch methanol and the like, which serves to remove residual acid and anyimpurities which might have been released by the process of dissolvingand reprecipitating the pigment. The solid resulting can then be driedby, for example, heating yielding a dark blue pigment of the desiredtitanyl phthalocyanine polymorph, the form of which was determined bythe composition of the precipitant solvent. The polymorphic form andpurity of the product was determined by XRPD analysis.

In an embodiment of the present invention, there is provided a processfor the preparation of titanyl phthalocyanine polymorphs, whichcomprises: 1) dissolving the precursor pigment, which can be any crystalform of TiOPc, in a mixture of trifluoroacetic acid and methylenechloride comprised of from 5 percent acid to about 25 percent acid and95 parts to 75 parts of methylene chloride, wherein the amount ofprecursor pigment is, for example, from 5 parts to about 25 parts of theprecursor pigment to 100 parts of acid solution, by adding the pigmentto the solution and stirring the mixture for an effective period oftime, for example from about 5 minutes to several days, and in anembodiment about two weeks, at a temperature of from about 0° to about50° C.; 2) pouring or adding the resultant solution into a rapidlystirred precipitant solvent in a ratio of from about 1 part of theaforementioned pigment solution to 2 parts of precipitant solution toabout 1 part pigment solution to about 50 parts of precipitant at atemperature of from about 0° to about 100° C. over a period of from 1minute to about 60 minutes to ensure rapid efficient mixing in anembodiment, the precipitant solution was stirred at a rate sufficient toform a deep vortex in the reaction vessel, and the pigment was poured ina slow stream into the side of the vortex; 3) following the addition,the resultant dispersion of the desired polymorphic form of TiOPc wasstirred at a temperature of from 0° to about 100° C. for a period offrom about 5 minutes to about 24 hours; 4) subsequently separating thetitanyl phthalocyanine from the mother liquor by filtration, for examplethrough a glass fiber filter in a porcelain filter funnel, and washingthe product titanyl phthalocyanine pigment in the funnel with aneffective amount of solvent, for example from about 20 parts of washsolvent to about 1 part of the starting pigment, such as methanol, toremove most of the acidic mother liquor; 5) redispersing the resultingwet cake in a solvent, such as methanol, acetone, water, and the like inan effective amount of, for example, from about 20 parts to about 100parts of solvent to 1 part of the pigment for a period of from about 5minutes to 24 hours at a temperature of from 0° C. to about 100° C., theprimary purpose of such washing being to further remove any residualacid or other impurities from the particular polymorphic form of TiOPcwhich resulted from the precipitation process; 6) isolating the desiredtitanyl phthalocyanine polymorph by, for example, filtration through aglass fiber filter as in step (4), and subsequently optionally washingthe solid product in the funnel with a solvent, such as water methanolor acetone, and the like to complete purification. The final product canbe obtained after the solid has been dried at a temperature of fromabout 25° to about 150° C. for a time of 1 hour to about 24 hours, forexample either in the air or under vacuum. A yield corresponding toabout 95 percent to about 75 percent of the weight of the startingpigment can obtained. The polymorphic form of the final pigment wasdetermined by XRPD analysis, reference Table 2.

A typical small-scale conversion reaction was accomplished in anembodiment of the present invention as follows:

Two grams of titanyl phthalocyanine synthesized by the process ofExample I, below, was dissolved in 20 milliliters of a 1:4 mixture (V/V)of trifluoroacetic acid in methylene chloride by stirring in a 25milliliters Erlenmeyer flask at room temperature for 5 minutes. Theresultant dark green solution, which did not contain any undissolvedmaterial, was then poured into 200 milliliters of methanol in a 250milliliter Erlenmeyer flask with vigorous stirring at room temperature.The resultant dark blue suspension was stirred at room temperature foran additional 30 minutes and then was filtered through a 4.25 centimeterglass fiber filter (Whatman GF/A grade) and the solid was washed on thefunnel with about 20 milliliters of methanol. The resultant wet filtercake was transferred to a 125 milliliter flask and was redispersed in 50milliliters of methanol. The resulting dispersion was stirred for 30minutes, then was refiltered as above, and the solid resulting waswashed on the funnel with methanol (20 milliliters) then water (2×20milliliters) and finally with methanol again (20 milliliters). The solidwas dried at 70° C. for 2 hours to yield about 1.8 grams of dark bluepigment. This was determined to be a new polymorphic form of TiOPc,designated herein as Type Z-1, reference the XRPD pattern of FIG. 2.

                  TABLE 2                                                         ______________________________________                                        EFFECT OF PRECIPITANT SOLVENT                                                 ON POLYMORPHISM                                                               Standard Experiment: 2 grams of TiOPc in 20 milliliters 1:4                   CF.sub.3 CO.sub.2 H/CH.sub.2 Cl.sub.2 poured into 200 milliliters             of precipitant solvent                                                        PRECIPITANT         XRPD ANALYSIS                                             ______________________________________                                        Water               Type IV                                                   Methanol            Type Z-1                                                  1:1 Methanol/Water  Type X                                                    95:5 Methanol/Water Type III (major)                                          Isopropanol         Type II                                                   Diethyl Ether       Type I                                                    1:1 Toluene/Water   Type IV                                                   1:1 Chlorobenzene/Water                                                                           Type IV                                                   1:1 Acetone/Water   Type III (major)                                          1:1 Ethanol/Water   Type X                                                    1:1 Isopropanol/Water                                                                             Type IV                                                   1:1 Ethylene Glycol/Water                                                                         Type Z-2                                                  1:1 Dimethylformamide/Water                                                                       Type III + Type IV                                        1:1 Dimethylsulfoxide/Water                                                                       Type III + Type IV                                        ______________________________________                                         *Hitherto unreported crystal forms                                       

When the above procedure was repeated with a series of differentprecipitants as illustrated in Table 2, the polymorphic form obtainedwas found to depend on the nature of the precipitant solvent. Thus,either of the known forms (Type I, II, III or IV) could be obtained asshown in Table 2. These were identified by comparing their XRPDs tothose of the known forms shown in FIGS. 1A, 1B, 1C and 1D. Precipitationinto ethylene glycol/water (1:1) also provided a hitherto undescribedpolymorph of TiOPc, designated as Type Z-2, the XRPD of which is shownin FIG. 3. A third new Type of titanyl phthalocyanine, obtained from a50:50 mixture of methanol or ethanol with water and which has been foundto afford xerographic devices having very high sensitivity to 780nanometers light, identified herein as the X form, had the XRPD patternshown in FIG. 4. Although the new Type X polymorph is similar to theType IV TiOPc in that it shows its strongest peak at the Bragg angle 2theta=27.3 degrees, it differs substantially from Type IV in that thepeaks at about 2 theta=9.5 and 9.7 degrees, which are quite pronouncedin the XRPD of Type IV titanyl phthalocyanine pigment and are absent inthe Type X material. Additionally, a peak in the Type X form at 2theta=about 7.4 degrees is relatively much more pronounced (compared toother peaks in the diffractograph) than the same peak in the Type IVXRPD shown in FIG. 1D. While these are the most predominant differencesbetween the Type IV and Type X polymorphs, other more subtle differencesapparent to those familiar with the interpretation of X-ray diffractionare also noticeable. Additionally, the X form shows broad diffractionpeaks at 2 theta values of 14.1 and 17.8 degrees. The 2 theta valuesreported refer to diffraction of Cu alpha radiation (wavelength=0.1542nanometers).

In another embodiment of the present invention, solutions of TiOPc in a1:4 mixture of trifluoroacetic acid and methylene chloride wereprecipitated into varying mixtures of methanol and water ranging from100 percent methanol to 100 percent water. Following the above describedisolation, the samples were analyzed by XRPD, and the results areprovided in Table 3 that follows.

                  TABLE 3                                                         ______________________________________                                        Precipitant                                                                   Solvent Ratio                                                                 MeOH/H.sub.2 O                                                                            XRPD Analysis                                                     ______________________________________                                        100:0       Type Z-1                                                          95:5        Type III (major)                                                  90:10       Type III (major)                                                  85:15       Type III (major)                                                  80:20       Type III (major)                                                  75:25       Type III (major)                                                  70:30       Type III (major)                                                  65.35       Type III (minor) + Type X                                         60:40       Type X                                                            55:45       Type X                                                            50:50       Type X                                                            45:55       Type X                                                            40:60       Type X                                                            35:65       Type X                                                            30:70       Type IV                                                           25:75       Type IV                                                           20:80       Type IV                                                            0:100      Type IV                                                           ______________________________________                                    

The data in this Table illustrate that at relatively high methanolconcentrations the preponderant polymorph formed is the Type III form.However, beginning at a composition of about 65 percent methanol 35percent water the Type X form predominates. Polymorphically pure Type Xis obtained when the acid solution is precipitated into methanol/watercompositions ranging from 60 to 35 percent methanol. Compositionscontaining less than about 35 percent methanol and pure water result inthe formation of the Type IV form which has the XRPD peaks at 2theta=9.8 degrees.

Another embodiment of the present invention is directed to a process forthe preparation of titanyl phthalocyanine, which comprises the reactionof diiminoisoindolene in a ratio of from 3 to 5 molar equivalents with 1molar equivalent of titanium tetrapropoxide in chloronaphthalene orN-methylpyrrolidone solvent in a ratio of from about 1 partdiiminoisoindolene to from about 5 to about 10 parts of solvent. Theseingredients are stirred and warmed to a temperature of from about 160°to 240° C. for a period of from about 30 minutes to about 8 hours. Afterthis time the reaction mixture is cooled to a temperature of from about100° to 160° C. and the mixture is filtered through a sintered glassfunnel (M porosity). The pigment is washed in the funnel with boilingdimethyl formamide (DMF) solvent in an amount which is sufficient toremove all deeply colored impurities from the solid as evidenced by achange in the color of the filtrate from an initial black color to afaint blue green. Following this, the pigment is stirred in the funnelwith boiling DMF in a sufficient quantity to form a loose suspension,and this is refiltered. The solid is finally washed with DMF at roomtemperature, then with a small amount of methanol and is finally driedat about 70° C. for from about 2 to about 24 hours. Generally, an amountof DMF equal to the amount of solvent (chloronaphthalene orN-methylpyrrolidone) used in the synthesis reaction is required for thewashing step. The yield from this synthesis is from 60 to about 80percent. X-ray powder diffraction, XRPD, analysis of the product thusobtained indicated that it was the Type I polymorph, or β Type titanylphthalocyanine.

In specific embodiments of the present invention, the following can beaccomplished:

Five grams of Type I TiOPc can be dissolved in 100 milliliters of a 1:4mixture (v/v) of trifluoroactic acid (TFA) and methylene chloride (CH₂Cl₂) to provide a dark green solution containing no undissolved TiOPc.The resulting solution was then divided into 5×20 milliliter portions.

A 20 milliliter portion of the above prepared solution was poured overabout a 2 minute period into 100 milliliters of a well stirred solutionof methanol in water (1:1, v/v). The resultant dark blue precipitate wasvacuum filtered through a 4.25 centimeter glass fiber paper in a Buchnerfunnel. The solid was washed on the funnel with:

a) 20 milliliters of 1:1 (v/v) water/methanol

b) 3×10 milliliter portions of methanol

c) 3×5 milliliter portions of deionized water

d) 2×5 milliliter portions of methanol

The resulting solid was dried at 70° C. for 16 hours to yield 0.95 gramof dark blue pigment. An XRPD analysis of this material showed that itwas the Type X polymorphic form of TiOPc.

A second portion, 20 milliliter aliquot, of the above prepared TFA/CH₂Cl₂ solution was poured into 100 milliliters of isopropyl alcohol. Theresulting precipitated blue powder was isolated and dried as indicatedherein except that the first washing used 20 milliliters of isopropanol.The product, 0.93 gram of blue powder, was identified as Type II TiOPcby XRPD.

A third portion, 20 milliliter aliquot, of the above prepared solutionwas poured into 100 milliliters of diethyl ether and the precipitatedproduct was isolated as indicated herein except that the first wash used20 milliliters of diethyl ether. The resultant 0.82 gram of blue powderwas identified as Type I TiOPc by XRPD.

A fourth portion, 20 milliliters aliquot, of the above prepared TFA/CH₂Cl₂ solution was added to 100 milliliters of chlorobenzene. A dark greensolution was obtained. This was treated with 20 milliliters of waterwith vigorous stirring and the resultant suspension was furtherprocessed as indicated herein except that the initial washing step, a),was omitted to yield 0.93 gram of blue pigment which was shown to beType IV TiOPc by XRPD.

A fifth portion, 20 milliliters, of the above TFA/CH₂ Cl₂ solution waspoured over a 1 minute period into a vigorously stirred suspension oftoluene in water (1:1, v/v). The precipitated solid was isolated exactlyas indicated herein. The product was 0.93 gram of blue solid which wasidentified as Type IV TiOPc by XRPD.

Type II TiOPc, as determined by XRPD, was synthesized by acid pasting asample of the Type I pigment in concentrated sulfuric acid. A 1.05 gramssample of the resulting material was dissolved in 20 milliliters of a1:4 mixture of trifluoroacetic acid and methylene chloride. Theresulting solution was poured into 200 milliliters of a 1:1 mixture ofmethanol and water. The precipitated solid was isolated exactly asindicated herein for Type X TiOPc to provide 1.02 gram of blue pigmentidentified as Type X TiOPc by XRPD.

Numerous different layered photoresponsive imaging members with thephthalocyanine pigments obtained by the processes of the presentinvention can be fabricated. In one embodiment, thus the layeredphotoresponsive imaging members are comprised of a supporting substrate,a charge transpoprt layer, especially an aryl amine hole transportlayer, and situated therebetween a photogenerator layer comprised oftitantyl phthalocyanine of Type X, Type Z-1, Type Z-2 or Type IV.Another embodiment of the present invention is directed to positivelycharged layered photoresponsive imaging members comprised of asupporting substrate, a charge transport layer, especially an aryl aminehole transport layer, and as a top overcoating titanyl phthalocyaninepigments Type X or Type IV obtained with the processes of the presentinvention. Moreover, there is provided in accordance with the presentinvention an improved negatively charged photoresponsive imaging membercomprised of a supporting substrate, a thin adhesive layer, a titanylphthalocyanine obtained by the processes of the present inventionphotogenerator dispersed in a polymeric resinous binder, and as a toplayer aryl amine hole transporting molecules dispersed in a polymericresinous binder.

The photoresponsive imaging members of the present invention can beprepared by a number of known methods, the process parameters and theorder of coating of the layers being dependent on the member desired.The imaging members suitable for positive charging can be prepared byreversing the order of deposition of photogenerator and hole transportlayers. The photogenerating and charge transport layers of the imagingmembers can be coated as solutions or dispersions onto selectivesubstrates by the use of a spray coater, dip coater, extrusion coater,roller coater, wire-bar coater, slot coater, doctor blade coater,gravure coater, and the like, and dried at from 40° to about 200° C. forfrom 10 minutes to several hours under stationary conditions or in anair flow. The coating is carried out in such a manner that the finalcoating thickness is from 0.01 to about 30 microns after it has dried.The fabrication conditions for a given layer will be tailored to achieveoptimum performance and cost in the final device.

Imaging members with the titanyl phthalocyanine pigments of the presentinvention are useful in various electrostatographic imaging and printingsystems, particularly those conventionally known as xerographicprocesses. Specifically, the imaging members of the present inventionare useful in xerographic imaging processes wherein the titanylphthalocyanines pigments absorb light of a wavelength of from about 600nanometers to about 900 nanometers. In these known processes,electrostatic latent images are initially formed on the imaging memberfollowed by development, and thereafter transferrng the image to asuitable substrate.

Moreover, the imaging members of the present invention can be selectedfor electronic printing processes with gallium arsenide light emittingdiode (LED) arrays which typically function at wavelengths of from 660to about 830 nanometers.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention and further featuresthereof, reference is made to the following detailed description ofvarious preferred embodiments wherein:

FIGS. 1A, 1B, 1C and 1D are diffractograph summaries of the XRPDs of theknown polymorphs, Type I, II, III and IV of titanyl phthalocyanine;

FIG. 2 is a diffractograph of the XRPD of the new Z-1 crystal form oftitanyl phthalocyanine obtained, for example, from precipitation into100 percent methanol;

FIG. 3 is a diffractograph of the XRPD of the new Z-2 crystal form oftitanyl phthalocyanine obtained, for example, by precipitation intowater/ethylene glycol;

FIG. 4 is a diffractograph of the XRPD of the new Type X polymorphtitanyl phthalocyanine;

FIG. 5 is a partially schematic cross-sectional view of a negativelycharged photoresponsive imaging member of the present invention; and

FIG. 6 is a partially schematic cross-sectional view of a positivelycharged photoresponsive imaging member of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Illustrated in FIG. 5 is a negatively charged photoresponsive imagingmember of the present invention comprised of a supporting substrate 1, asolution coated adhesive layer 2 comprised, for example, of a polyester49,000 available from Goodyear Chemical, a photogenerator layer 3comprised of titanyl phthalocyanine, such as Type IV, Type Z-1, Z-2, orX obtained with the process of the present invention, reference ExampleIV for example, optionally dispersed in an inactive resinous binder, anda hole transport layer 5, comprised of N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine, dispersed in a polycarbonateresinous binder 7.

Illustrated in FIG. 6 is a positively charged photoresponsive imagingmember of the present invention comprised of a substrate 10, a chargetransport layer 12, comprised of N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine dispersed in a polycarbonate resinousbinder 14, and a photogenerator layer 16 obtained with the process ofthe present invention, optionally dispersed in an inactive resinousbinder 18.

Substrate layers selected for the imaging members of the presentinvention can be opaque or substantially transparent, and may compriseany suitable material having the requisite mechanical properties. Thus,the substrate may comprise a layer of insulating material includinginorganic or organic polymeric materials, such as Mylar a commerciallyavailable polymer, Mylar containing titanium, a layer of an organic orinorganic material having a semiconductive surface layer such as indiumtin oxide, or aluminum arranged thereon, or a conductive materialinclusive of aluminum, chromium, nickel, brass or the like. Thesubstrate may be flexible, seamless, or rigid and many have a number ofmany different configurations, such as for example a plate, acylindrical drum, a scroll, an endless flexible belt and the like. Inone embodiment, the substrate is in the form of a seamless flexiblebelt. In some situations, it may be desirable to coat on the back of thesubstrate, particularly when the substrate is a flexible organicpolymeric material, an anticurl layer, such as for example polycarbonatematerials commercially available as Makrolon.

The thickness of the substrate layer depends on many factors, includingeconomical considerations, thus this layer may be of substantialthickness, for example, over 3,000 microns; or of minimum thicknessproviding there are no adverse effects on the system. In one embodiment,the thickness of this layer is from about 75 microns to about 300microns.

With further regard to the imaging members, the photogenerator layer ispreferably comprised of the titanyl phthalocyanine pigments obtainedwith the processes of the present invention dispersed in resinousbinders. Generally, the thickness of the photogenerator layer depends ona number of factors, including the thicknesses of the other layers andthe amount of photogenerator material contained in this layer.Accordingly, this layer can be of a thickness of from about 0.05 micronto about 10 microns when the titanyl phthalocyanine photogeneratorcomposition is present in an amount of from about 5 percent to about 100percent by volume. In one embodiment, this layer is of a thickness offrom about 0.25 micron to about 1 micron, when the photogeneratorcomposition is present in this layer in an amount of 30 to 75 percent byvolume. The maximum thickness of this layer in an embodiment isdependent primarily upon factors, such as photosensitivity, electricalproperties and mechanical considerations. The charge generator layer canbe obtained by dispersion coating the TiOPc obtained with the processesof the present invention, and a binder resin with a suitable solvent.The binder may be omitted. The dispersion can be prepared by mixingand/or milling the TiOPc in equipment such as paint shakers, ball mills,sand mills and attritors. Common grinding media such as glass beads,steel balls or ceramic beads may be used in this equipment. The binderresin may be selected from a wide number of polymers such as poly(vinylbutyral), poly(vinyl carbazole), polyesters, polycarbonates, poly(vinylchloride), polyacrylates and methacrylates, copolymers of vinyl chlorideand vinyl acetate, phenoxy resins, polyurethanes, poly(vinyl alcohol),polyacrylonitrile, polystyrene, and the like. The solvents to dissolvethese binders depend upon the particular resin. In embodiments of thepresent invention, it is desirable to select solvents that do not effectthe other coated layers of the device. Examples of solvents useful forcoating TiOPc dispersions to form a photogenerator layer are ketones,alcohols, aromatic hydrocarbons, halogenated aliphatic hydrocarbons,ethers, amines, amides, esters, and the like. Specific examples arecyclohexanone, acetone, methyl ethyl ketone, methanol, ethanol, butanol,amyl alcohol, toluene, xylene, chlorobenzene, carbon tetrachloride,chloroform, methylene chloride, trichloroethylene, tetrahydrofuran,dioxane, diethyl ether, dimethylformamide, dimethylacetamide, butylacetate, ethyl acetate and methoxyethyl acetate, and the like.

The coating of the TiOPc dispersion in embodiments of the presentinvention can be accomplished with spray, dip or wirebar methods suchthat the final dry thickness of the charge generator layer is from 0.01to 30 microns and preferably from 0.1 to 15 microns after being dried at40° to 150° C. for 5 to 90 minutes.

Illustrative examples of polymeric binder resinous materials that can beselected for the photogenerator pigment include those polymers asdisclosed in U.S. Pat. No. 3,121,006, the disclosure of which is totallyincorporated herein by reference.

As adhesives, there can be selected various known substances inclusiveof polyesters, polyamides, poly(vinyl butyral), poly(vinyl alcohol),polyurethane and polyacrylonitrile. This layer is of a thickness of fromabout 0.05 micron to 1 micron. Optionally, this layer may containconductive and nonconductive particles such as zinc oxide, titaniumdioxide, silicon nitride, carbon black, and the like to provide, forexample, in embodiments of the present invention desirable electricaland optical properties.

Aryl amines selected for the hole transporting layer which generally isof a thickness of from about 5 microns to about 75 microns, andpreferably of a thickness of from about 10 microns to about 40 microns,include molecules of the following formula: ##STR1## dispersed in ahighly insulating and transparent organic resinous binder wherein X isan alkyl group or a halogen, especially those substituents selected fromthe group consisting of (ortho) CH₃, (para) CH₃, (ortho) Cl, (meta) Cl,and (para) Cl.

Examples of specific aryl amines areN,N'-diphenyl-N,N'-bis(alkylphenyl)-1,1-biphenyl-4,4'-diamine whereinalkyl is selected from the group consisting of methyl, such as 2-methyl,3-methyl and 4-methyl, ethyl, propyl, butyl, hexyl, and the like. Withchloro substitution, the amine is N,N'-diphenyl-N,N'-bis(halophenyl)-1,1'-biphenyl-4,4'-diamine wherein halo is 2-chloro, 3-chloro or4-chloro. Other known hole transporting componds can be selected.

Examples of the highly insulating and transparent resinous material orinactive binder resinous material for the transport layers includematerials such as those described in U.S. Pat. No. 3,121,006, thedisclosure of which is totally incorporated herein by reference.Specific examples of organic resinous materials include polycarbonates,acrylate polymers, vinyl polymers, cellulose polymers, polyesters,polysiloxanes, polyamides, polyurethanes and epoxies as well as block,random or alternating copolymers thereof. Preferred electricallyinactive binders are comprised of polycarbonate resins having amolecular weight of from about 20,000 to about 100,000 with a molecularweight of from about 50,000 to about 100,000 being particularlypreferred. Generally, the resinous binder contains from about 10 toabout 75 percent by weight of the active material corresponding to theforegoing formula, and preferably from about 35 percent to about 50percent of this material.

Also, included within the scope of the present invention are methods ofimaging and printing with the photoresponsive devices illustratedherein. These methods generally involve the formation of anelectrostatic latent image on the imaging member, followed by developingthe image with a toner composition, reference U.S. Pat. Nos. 4,560,635;4,298,697 and 4,338,390, the disclosures of which are totallyincorporated herein by reference, subsequently transfering the image toa suitable substrate, and permanently affixing the image thereto. Inthose environments wherein the device is to be used in a printing mode,the imaging method involves the same steps with the exception that theexposure step can be accomplished with a laser device or image bar.

The invention will now be described in detail with reference to specificpreferred embodiments thereof, it being understood that these examplesare intended to be illustrative only. The invention is not intended tobe limited to the materials, conditions, or process parameters recitedherein, it being noted that all parts and percentages are by weightunless otherwise indicated.

EXAMPLE I Synthesis of Type I Titanyl Phthalocyanine

To a 300 milliliter three-necked flask fitted with mechanical stirrer,condenser and thermometer maintained under an argon atmosphere was added32.7 grams (grams) (0.225 mole) of 1,3-diiminoisoindolene, 170milliliters of N-methyl pyrrolidone and 15.99 grams (0.056 mole) oftitanium tetrapropoxide (all the aforementioned reagents are availablefrom Aldrich Chemical Company). The resulting mixture was stirred andwarmed to reflux (about 198° C.) for 2 hours. The resultant blacksuspension was cooled to about 160° C. then was filtered by suctionthrough a 350 milliliter M-porosity sintered glass funnel which had beenpreheated with boiling dimethyl formamide (DMF). The solid resulting waswashed with two 150 milliliter portions of boiling DMF and the filtrate,initially black, became a light blue-green color. The solid was slurriedin the funnel with 150 milliliters of boiling DMF and the suspension wasfiltered. The resulting solid was washed in the funnel with 150milliliters of DMF at 25° C. then with 50 milliliters of methanol. Theresultant shiny dark blue solid was dried at 70° C. overnight to yield17.4 grams (54 percent) of pigment which was identified as Type I TiOPcon the basis of its XRPD. The elemental analysis of the product was: C,66.44; H, 2.62; N, 20.00; Ash (TiO₂), 12.35. TiOPc requires: C, 66.67;H, 2.80; N, 19.44; Ash, 13.86.

EXAMPLE II Synthesis of Type I Titanyl Phthalocyanine

A 1 liter three-necked flask fitted with mechanical stirrer, condenserand thermometer maintained under an atmosphere of argon was charged withdiiminoisoindolene (94.3 grams, 0.65 mole), titanium tetrabutoxide (55.3grams, 0.1625 mole; Aldrich) and 650 milliliters of 1-chloronaphthalene.The mixture was stirred and warmed. At about 140° C. the mixture turneddark green and began to reflux. At this time the condenser was removedand the vapor (this was identified as n-butanol by gas chromatography)was allowed to escape until the reflux temperature reached 230° C. Thereaction was maintained at about this temperature for one and one halfhours then was cooled to 15° C. Filtration using a 1 liter sinteredglass funnel and washing with boiling DMF, then methanol, as in theabove Example I provided 69.7 grams (74 percent yield) of blue pigmentwhich was identified as Type I TiOPc by XRPD.

The elemental analysis of the product was: C, 67.38; H, 2.78; N, 19.10;Ash, 13.61. TiOPC requires: C, 66.67; H, 2.80; N, 19.44; Ash, 13.61.

EXAMPLE III Preparation of Type X Titanyl Phthalocyanine

To a solution of trifluoroacetic acid (100 milliliters) in methylenechloride (400 milliliters) stirred with a magnet in a 1 liter Erlenmeyerflask was added 50 grams of Type I TiOPc, synthesized as in Example I,over a 2 minute period. No heat was evolved and the resultant dark greensolution was stirred at room temperature for 15 minutes. The solutionwas poured over a 2 minute period into a solution of methanol (2.5liters) and water (2.5 liters), contained in a 12 liter glass cylinder,which was stirred with a 100 millimeters long magnetic stir bar at arate which was sufficient to create a vortex, which extended almost tothe bottom of the flask. Following the addition, the resultant bluesuspension was stirred at room temperature for 45 minutes, then wasallowed to stand undisturbed for 25 minutes. The yellowish brownsupernatant liquid was almost completely separated from the precipitatedsolid by carefully decanting the reaction vessel. The remaining blueresidue was redispersed in 2 liters of methanol by stirring with amagnet for 1 hour at room temperature. The resultant suspension wasfiltered through an 18 centimeter glass fiber filter in a porcelainfilter funnel and the filter cake was washed in succession with 2×100milliliters of methanol, 2×100 milliliters of water, 500 milliliters ofwater, then 2×100 milliliters of methanol. The product was dried at 75°C. overnight to provide 47.6 grams (95 percent yield) of dark bluepigment which was identified as Type X TiOPc by XRPD.

EXAMPLE IV Preparation of Type IV TiOPc

A 20 milliliters aliquot of a solution of 10 grams of Type I TiOPc,prepared in N-methylpyrrolidone solvent as in Example I, in 100milliliters of a mixture of trifluoroacetic acid in methylene chloride(1:4, v/v) was added over a 2 minute period to a rapidly-stirredsolution of methanol (45 milliliters) and water (135 milliliters). Theresultant coarse suspension was stirred at room temperature for 35minutes then was allowed to settle. The supernatant liquid was decantedand the blue residue was redispersed in 100 milliliters of methanol bystirring for 15 minutes. The suspension was filtered using a 7centimeters diameter glass fiber filter in a porcelain funnel. The solidwas washed in the funnel with 2×10 milliliter portions of methanol, 4×20milliliter portions of deionized water and 2×10×20 milliliter portionsof water and 2×10 milliliter portions of methanol. The solid was driedat 75° C. to yield 1.85 gram of blue pigment identified as Type IV TiOPcby XRPD.

EXAMPLE V Preparation of Type Z-1 TiOPc

A 20 milliliter aliquot of the acid solution of TiOPc of Example IV waspoured over about 1 minute into 100 milliliters of methanol, which wasrapidly stired at room temperature in a 125 milliliter Erlenmeyer flask.The resultant dispersion was stirred for 45 minutes, then was filteredusing a 7 centimeter glass fiber filter. The solid was washed in thefunnel with 2×10 milliliter portions of methanol, 4×20 milliliterportions of water and 2×10 milliliter portions of methanol. The productwas dried at 70° C. to provide 2.09 grams of blue pigment identified asType Z-1 TiOPc by XRPD.

EXAMPLE VI Preparation of Type Z-2 TiOPc

A solution was prepared by dissolving 6 grams of Type I TiOPc,synthesized as in Example I, in 60 milliliters of a 1:4 mixture (v/v) oftrifluoroacetic acid and methylene chloride. A 10 milliliter portion ofthis solution was precipitated into 100 milliliters of a 1:1 mixture ofwater and ethylene glycol. Phase separation occurred and the pigment andmethylene chloride formed sticky lumps on the bottom of the reactionflask. The mixture was stirred for 30 minutes, then the supernatantliquid was decanted and the pigment phase was redispersed in 50milliliters of methanol. Filtration, washing with water and methanol anddrying as in the above three Examples provided 0.90 gram of almost blacksolid which was identified as a new crystal form of TiOPc, characterizedas Type Z-2, from its XRPD.

The titanyl phthalocyanines were evaluated as photogenerators inxerographic imaging devices which were prepared by the followingprocedure. An aluminized Mylar substrate was coated with a Nylon 8solution, prepared by dissolving 5 grams of Nylon 8 (Dainippon Ink andChemical Company) in 24 grams of n-butanol and 4 grams of water using a1 mil gap applicator. This layer was dried at 135° C. for 20 minutes;the final thickness was measured to be 0.6 micron. A dispersion of theTiOPc was prepared by ball milling 0.35 gram of the TiOPc, respectively,and poly(vinyl butyral) in 13.4 grams of butyl acetate in a 30milliliter jar containing 70 grams of 1/8 inch stainless steel balls.The dispersion was milled for 20 hours then was coated onto the Nylon 8layer described above using a 1 mil applicator. The thus formedphotogenerating layer was dried at 100° C. for 10 minutes: its finalthickness was determined to be about 0.40 micron.

Hole transporting layers solution were prepared by dissolving 5.4 gramsof N,N'-diphenyl-N,N-bis(3-methyl phenyl)-1,1'-biphenyl-4,4'-diamine,8.1 grams of polycarbonate in 52 grams of chlorobenzene. The solutionwas coated onto the TiOPc generator layer using an 8 mil filmapplicator. The charge transporting layer thus obtained was dried at115° C. for 60 minutes to provide a final thickness of about 23 microns.

The xerographic electrical properties of a photoresponsive imagingmember prepared as described above were determined by electrostaticallycharging the surface thereof with a corona discharge source until thesurface potential, as measured by a capacitatively coupled probeattached to an electrometer, attained an initial dark value, V₀, of -800volts. After resting for 0.5 seconds in the dark, the charged memberreached a surface potential, V_(ddp), or dark development potential. Themember was then exposed to filtered light from a Xenon lamp. A reductionin surface potential from V_(ddp) to a background potential, V_(bg), dueto the photodischarge effect, was observed. The dark decay in volts persecond was calculated as (V₀ -V_(ddp))/0.5. The percent ofphotodischarge was calculated as 100×(V_(ddp) -V_(bg))/V_(ddp). Thehalf-exposure energy, E_(1/2), the required exposure energy causingreduction of the V_(ddp) to half of its initial value, was determined.The wavelength of light selected for our measurements was 800nanometers.

EXAMPLE VII

A xerographic device prepared and evaluated as described in Example VIwherein the photogenerating pigment was Type X TiOPc described inExample III, had the following properties: V_(ddp), 805 volts; darkdecay, 27 volts/second; E1/2, 1.3 Erg/cm2

EXAMPLE VIII

A xerographic device, prepared and evaluated as described from the TypeIV TiOPc described in Example IV, had the following properties: Vddp,803 volts; dark decay, 56 volts/second; E1/2, 1.5 Ergs/cm2.

Other modifications of the present invention may occur to those skilledin the art based upon a review of the present application and thesemodifications, including equivalents thereof, are intended to beincluded within the scope of the present invention.

What is claimed is:
 1. A process for the preparation of titanylphthalocyanine Type I, Type II, Type III, Type IV, Type X, Type Z-1, andType Z-2, which consists essentially of dissolving a titanylphthalocyanine in a solution of trifluoroacetic acid and methylenechloride; adding the resultant solution to a solvent or solvent mixturethat will enable precipitation; and separating the product titanylphthalocyanine from the solution followed by an optional washing.
 2. Aprocess for the preparation of titanyl phthalocyanine Type I, Type II,Type III, Type IV, Type X, Type Z-1, and Type Z-2, which consistsessentially of adding a titanyl phthalocyanine to a solution oftrifluoroacetic acid and methylene chloride; adding the resultantsolution to a solvent or solvent mixture that will enable precipitation;and separating the product titanyl phthalocyanine from the solutionfollowed by an optional washing.
 3. A process in accordance with claim 1wherein the product titanyl phthalocyanine is a Type IV polymorph.
 4. Aprocess in accordance with claim 2 wherein the product titanylphthalocyanine is a Type IV polymorph.
 5. A process in accordance withclaim 1 wherein the product titanyl phthalocyanine is a Type IIIpolymorph.
 6. A process in accordance with claim 2 wherein the producttitanyl phthalocyanine is a Type III polymorph.
 7. A process inaccordance with claim 1 wherein the product titanyl phthalocyanine is aType II polymorph.
 8. A process in accordance with claim 2 wherein theproduct titanyl phthalocyanine is a Type II polymorph.
 9. A process inaccordance with claim 1 wherein the product titanyl phthalocyanine is aType I polymorph.
 10. A process in accordance with claim 2 wherein theproduct titanyl phthalocyanine is a Type I polymorph.
 11. A process inaccordance with claim 1 wherein the product titanyl phthalocyanine is aType Z-1 polymorph.
 12. A process in accordance with claim 2 wherein theproduct titanyl phthalocyanine is a Type Z-1 polymorph.
 13. A process inaccordance with claim 1 wherein the product titanyl phthalocyanine is aType Z-2 polymorph.
 14. A process in accordance with claim 2 wherein theproduct titanyl phthalocyanine is a Type Z-2 polymorph.
 15. A process inaccordance with claim 1 wherein the product titanyl phthalocyanine is aType X polymorph.
 16. A process in accordance with claim 2 wherein theproduct titanyl phthalocyanine is a Type X polymorph.
 17. A process forthe preparation of titanyl phthalocyanine Type IV which consistsessentially of dissolving titanyl phthalocyanine Type I in a solution oftrifluoroacetic acid and methylene chloride; adding the solution to astirred mixture of an alcohol and water whereby a precipitate results;and separating the product titanyl phthalocyanine Type IV from thesolution followed by an optional washing.
 18. A process for thepreparation of titanyl phthalocyanine Type I, Type II, Type III, TypeIV, Type X, Type Z-1, and Type Z-2, which consists essentially of addinga titanyl phthalocyanine to a solution of trihaloacetic acid and ahalogenated hydrocarbon; adding the resultant solution to a solvent orsolvent mixture that will enable precipitation; and separating theproduct titanyl phthalocyanine from the solution followed by an optionalwashing.
 19. A process in accordance with claim 17 wherein the titanylphthalocyanine is dissolved in a mixture of trifluoroacetic acid andmethylene chloride.
 20. A process in accordance with claim 18 whereinthe titanyl phthalocyanine is dissolved in a mixture of trifluoroaceticacid and methylene chloride.
 21. A process in accordance with claim 17wherein the titanyl phthalocyanine is dissolved in a mixture oftrichloroacetic acid and methylene chloride.
 22. A process in accordancewith claim 18 wherein the titanyl phthalocyanine is dissolved in amixture of trichloroacetic acid and methylene chloride.
 23. A process inaccordance with claim 1 wherein the titanyl phthalocyanine is dissolvedin a 1:4 mixture of trifluoroacetic acid and methylene chloride.
 24. Aprocess in accordance with claim 2 wherein the titanyl phthalocyanine isdissolved in a 1:4 mixture of trifluoroacetic acid and methylenechloride.
 25. A process in accordance with claim 18 wherein the solventor solvent mixture is water and methanol.
 26. A process in accordancewith claim 18 wherein the solvent or solvent mixture is water andmethanol in a ratio of 1:1 by volume.
 27. A process in accordance withclaim 18 wherein the solvent or solvent is a mixture of water andmethanol containing from 65 percent to 35 percent methanol.
 28. Aprocess in accordance with claim 18 wherein the solvent is water.
 29. Aprocess in accordance with claim 18 wherein the solvent is methanol. 30.A process in accordance with claim 18 wherein the solvent or solventmixture is water and ethanol.
 31. A process in accordance with claim 18wherein the solvent is diethyl ether.
 32. A process in accordance withclaim 18 wherein the solvent is isopropyl alcohol.
 33. A process inaccordance with claim 18 wherein the solvent or solvent is a mixture ofwater and ethylene glycol.
 34. A process in accordance with claim 18wherein separation is accomplished by filtration.
 35. A process inaccordance with claim 18 wherein the solvent or solvent mixture iscomprised of a mixture of water and a polar aprotic solvent selectedfrom the group dimethyl sulfoxide, dimethyl formamide andN-methylpyrrolidone.
 36. A process in accordance with claim 1 whereinwashing is accomplished with a mixture of water and an alcohol.
 37. Aprocess in accordance with claim 2 wherein washing is accomplished witha mixture of water and an alcohol.
 38. A process in accordance withclaim 2 wherein washing is accomplished with water and an aromaticsolvent selected from the group consisting of benzene, toluene orchlorobenzene.
 39. A process in accordance with claim 2 wherein theproduct titanyl phthalocyanine is dried by heating.
 40. A process inaccordance with claim 2 wherein the product titanyl phthalocyanine isdried by heating at a temperature of from about 70° C. to about 150° C.41. A process in accordance with claim 2 wherein the product titanylphthalocyanine is dried by heating at a temperature of from about 70° C.to about 150° C. for a period of from about 1 to about 15 hours.
 42. Aprocess for the preparation of titanyl phthalocyanine Type IV whichconsists essentially of dissolving a titanyl phthalocyanine Type I, TypeII, Type III, Type IV, or Type X in a solution of trifluoroacetic acidand methylene chloride; adding the solution to a stirred mixture of analcohol and water whereby a precipitate results; and recovering saidtitanyl phthalocyanine.
 43. A process for the preparation of titanylphthalocyanine Type I, Type II, Type III, Type IV, Type X, Type Z-1, andType Z-2, which consists essentially of adding a titanyl phthalocyanineto a solution of trifluoroacetic acid and a chlorinated hydrocarbon;adding the resultant solution to a solvent or solvent mixture that willenable precipitation; and recovering said titanyl phthalocyanine.
 44. Aprocess in accordance with claim 42 wherein washing of the titanylphthalocyanine is accomplished.
 45. A process in accordance with claim44 wherein washing of the titanyl phthalocyanine is accomplished withwater and organic solvents.
 46. A process in accordance with claim 42wherein there results the titanyl phthalocyanines Type I, II, III, orIV.
 47. A process in accordance with claim 42 wherein there results thetitanyl phthalocyanine Type X.
 48. A process in accordance with claim 42wherein there results the titanyl phthalocyanine Type Z-1.
 49. A processin accordance with claim 42 wherein there results the titanylphthalocyanine Type Z-2.
 50. A process in accordance with claim 42wherein recovery is accomplished by filtration.
 51. A process inaccordance with claim 43 wherein recovery is accomplished by filtration.52. A process for the preparation of titanyl phthalocyanine whichconsists essentially of dissolving a titanyl phthalocyanine Type I, TypeII, Type III, or Type IV in a solution of trifluoroacetic acid andmethylene chloride; adding the solution to a stirred solvent or solventmixture whereby a precipitate of titanyl phthalocyanine of Types I, II,III, or IV results; and recovering said titanyl phthalocyanine.
 53. Aprocess for the preparation of titanyl phthalocyanine which consistsessentially of dissolving a titanyl phthalocyanine Type X, Type Z-1, orType Z-2 in a solution of trifluoroacetic acid and methylene chloride;adding the solution to a stirred solvent or solvent mixture whereby aprecipitate of titanyl phthalocyanine of Types X, Z-1, or Z-2 results;and recovering said titanyl phthalocyanine.
 54. A process in accordancewith claim 45 wherein washing of the titanyl phthalocyanine isaccomplished with alcohols, carbonyl compounds, ethers, esters, aromaticcompounds and polar aprotic solvents.